Guard arrangement for machine tools



June 11, 1940. H, BLOCQD 2,203,979

GUARD ARRANGEMENT FOR MACHINE TOOLS Filed Oct. 2, 1939 Patented June 11, 1940 UNITED STATES PATENT OFFICE GUARD ARRANGEMENT FOR MACHINE TOOLS Harold L. Blood, Worcester, Mass, assignor to The Heald Machine Company, Worcester, Mass, a corporation of Massachusetts Application october z, 1939, Serial No. 297,430

7 Claims. (01. 51 -2 72) or workpiece.

Other and further objects and advantages of the invention willmore fully appear from the following detailed description thereof, taken in connection with the accompanying drawing in which Fig. 1 is a front elevational view of an internal grinding machine, provided with the guardarrangement of my invention, and

Fig. 2 is a fragmentary large scale sectional View of the guard devices shown in Fig. 1. Like reference characters refer to like parts in the different figures. A 7

Referring to. Fig.1, the internal grinding machine there shown comprises a base I, having longitudinal ways, not shown, whereon is, supported, for reciprocatory movement, a table 2.

Mounted on said table is a workhead 3 wherein is journalled a shaft or spindle 4 whose inner end carries any suitable work holder or chuck 5 for the work a whose bore is to be ground. Any

suitable means such as an electric motor 6 and a driving belt 1 may be employed to drive the spindle 4 thus to obtain rotation of the workpiece a, while its bore is being ground.

Such grinding is effectedby a grinding Wheel 8, carried on the end of a rotary spindle 9 which is suitably journalled in a wheelhead, ID and driven at high speed. The wheelhead is mounted on a bridge I l which is supported by the mach ne base I. Said bridge spans the table 2 and its ways, thus permitting the necessary back and forth movements of the table by which to obtain the grinding wheels disposal within the workpiece bore, the usual relative reciprocatory traverse between wheel and work during the grinding operation, and the subsequent separation of same, to the position illustrated by Fig. l, for the re moval of the ground workpiece and the chucking of an unground workpiece.

imparted by mechanism such as that shown and described in the Blood Patent No. 2,011,705 dated 3 The table motions to effect this cycle of operations may be August 20, 1935, and it will further be understood that a progressive'radial or cross feed between the grinding wheel and the surface of the workpiece bore, while said parts are in grinding position, is imparted, as by means of a feedscrew I2, Fig. 1, by which the wheelhead IE! is shifted at right angles to the axis of the wheel spindle 9.

i In the above and similar internal grinding machine organizations it has been common practice to provide the workhead with an open-ended 10 guard, somewhat as shown in the drawings at l3,

said guard substantially surounding therotating chuck 5 and serving as a partial shield against the operators accidental contact with the moving partsas well as to interceptsome of the cool- 16 ant thrown off during the grinding operation. But heretofore, much of this coolant has splashed out through the front of such a guard, which must be left open for the grinding wheels entrance to and exit from the workpiece bore. 20 i It has also been the practice, in internal grinding machinesto provide the rotating wheel, when l in its withdrawn or non-grinding position, with a guard, substantially as shown and described in Heald et al., Pat. #l.,250,168; but the necessity of periodically swinging such a guard to inoperative, position, to permit the relative approach movements of wheels andwork, exposes the operator at such times to the dangers; of Wheel breakage, as well as to accidental contact with the unguarded wheel.

My invention does away with all these short comings of the priorguard arrangements. Ac-

cording to my invention the wheelhead IU has secured thereto, as by means of nuts I M a fixed guard or shield I5, encircling the wheel 8, and having a front opening l6- of sufficient diameter to permit free passage therethrough of the chuck 5. In similar fashion, the front opening I? of the work guard I3 is ofsuflicient diameter to pass freely overthe outside surface of the wheel guard IS, the latter substantially filling and closing said opening I! when the table movement has disposed the work a in the operative or grinding position, as indicated by the broken lines inFig. 2. In this position the wheel guard I 5 surrounds the chuck and is in turn surrounded by the work guard I 3, the telescoping relation of the two guards serving very eifectively to inany accidental contact with either the rotating wheel or the rotating work.

It is customary, in such grinding machines to periodically subject the grinding wheel, when separated from the work, to a dressing and truing operation, as by traversing its cutting surface with a diamond point I8, mounted in a suitable pivoted holder IS on the table 2. At appropriate intervals said holder H] which normally occupies v In my improved guard arrangement as above described, the opening I! of work guard l3 needs to be only very slightly larger than the wheel guard l5, a clearance of a few thousands of an inch being suflicient to permit such radial or cross feed of the wheelhead I0 as is ordinarily produced by the feed screw l2. A similar slight clearance suffices between the workholder 5 and the opening IQ of wheel guard I5. I

I claim:

1. In a machine tool, a rotary Work holder, a rotary tool, means for shifting said parts substantially axially, to alternately place. said tool inoperative position relative to the work in said holder and to separate said tool from said work, and an encircling guard for said tool, adapted in said operative position to encircle said work holder.

2. In a machine tool, a rotary WOIkhOldGl, a rotary tool, means for shifting said parts substan tially axially, to alternately place said tool in operative position relative to the work in said holder and to separate said tool from said work, and guards encircling respectively said work holder and said tool, said guards in said operative position being in telescopic relation.

In a machine tool, a rotary work holder, a rotary tool, means for shifting said parts substantially axially, to alternately place said tool rotary tool, means for shifting said parts substantially axially, to alternately place said tool in operative position relative to the work in said holder and to separate said tool from said work,

' and guard means for said work holder and tool respectively, said guard means cooperating in said operative position to totally enclose said work holder and said tool.

5. In a machine tool, a rotary work holder, a rotary tool, means for shifting said parts substantially axially, to alternately place said tool in operative position relative to the work in said holder and to separate said tool from said work, and a guard encircling said tool and spaced therefrom, the space between said guard'and said tool in the latters operative position being occupied by said work holder.

6. In an internal grinding machine, a rotary work holder and a rotary grinding wheel, said parts being relatively shiftable in substantially axial directions to engage and disengage said wheel with the work in said holder, a guard dework holder and a rotary grinding wheel, said parts being relatively shiftable in substantially axial directions to engage and disengage said wheel with the work in said holder, a guard for said wheel encircling the latter at all times, and a dressing device engageable periodically with said, wheel through an opening in said guard.

HAROLD L. BLOOD. 

